In the field of displays, the technology of Active Matrix Organic Light Emitting Diode (AMOLED) has the advantages of broad color gamut, high contrast, energy-saving, and foldability. It is one of the most competitive technology in the new generation of display technology.
In the current technology, the driving circuit of the AMOLED mostly has a 7T1C structure. That is the structure in a pixel compensation circuit includes seven thin film transistors (TFT) and one capacitor. The circuit of the structure not only can effectively compensate the pixel but also can effectively compensate the voltage threshold of the driving TFT to improve the image quality. However, compared with a driving circuit of a liquid crystal display (LCD) having a 1T1C structure, the driving circuit of the AMOLED has the following problems: the structure is complex, there are large amount of TFTs in a limited space, the connection is complicated, and the metal exposed area is too small. As a result, it is more difficult to detect the electrical characteristics of the TFT (such as the drive TFT) in the display area.